[Bobjork]

So ok, maybe I was wrong about the radius but still, some other explanations are given as well.
It was built in 1891 with horse trams. It was probably cheaper with metre gauge and it needed less space (width) than a 1435 or 1524mm tramway would.
I guess that is the only explanation. Even if a lot of cities have standard gauge tramways.
Because a lot of cities have metre gauge too. Probably something was behind the decision made at that time.

In sweden the reason for building narrow gauge railway often was economy.
In some rare cases they later widened the railway but in at least one case a standard gauge tramway was changed to a narrow gauge railway.